1. Technical Field
This invention relates to mechanical apparatus for changing the speed and torque of the output shaft of a prime mover relative to its input shaft. More specifically, this invention is directed to an apparatus for providing up to an infinite number of seamless, ripple free changes of speed and torque from a power source such as a gas or diesel engine, an electric motor, a jet engine, a steam engine, the crank of a bicycle, or the like.
2. Background Art
Historically, significant efforts have been directed to the provision of transmission assemblies adapted for changing the speed and torque of a power source. Many of these assemblies have involved the use of ratchet drives, eccentrically-oriented cam assemblies, and variable length lever arms. Representative of past efforts in this regard are the structures disclosed in the following issued patents: U.S. Pat. No. 629,389; U.S. Pat. No. 3,803,931; U.S. Pat. No. 4,630,830; U.S. Pat. No. 4,487,085; U.S. Pat. No. 6,068,570; U.S. Pat. No. 4,936,155.
For example, U.S. Pat. No. 629,389 discloses a bicycle in which it is stated, “The gear may be changed by substituting larger or smaller pulleys.” Thus, one would have to get off the bike, take out his tool kit, take-off the pulleys and attach new and different pulleys to change gear ratios. Furthermore, U.S. Pat. No. 629,389 is a one speed transmission.
U.S. Pat. No. 4,936,155 discloses a transmission to provide constant power, speed changing and torque multiplication. The invention utilizes “a variable throw cam and cam follower system to provide ripple free output speeds and wide ranging torques.” The cam follower wheel makes point contact with said cam. With this configuration, the cam follower of the present transmission makes line contact with the cam, thus limiting torque and power capacity.
U.S. Pat. No. 3,803,931 discloses “a variable speed transmission device comprises an output shaft rotated from a first eccentric member through unidirectional couplings”, thus rippled output speeds.
In U.S. Pat. No. 4,487,085, “The cam is tapered from one end to the other to permit the gear ratio of the transmission to be varied in infinite increments by adjusting the position of the cam relative to the followers.” Power must pass the power through a tiny point of contact greatly limiting the power capacity of the transmission.
In U.S. Pat. No. 4,630,839, “A bicycle having pivoted level pedal system (1, 2, 45) and lever arm length or gear ratio (speed) change devices (3, 4, 5, 6)” is disclosed.
The device of U.S. Pat. No. 4,630,839 does not provide any means for removing ripple and, therefore, cannot provide seamless, ripple free outputs.
U.S. Pat. No. 6,068,570 utilizes eccentrics 14 and 25 which it refers to as cams. The eccentrics 14 and 25 cannot provide ripple free outputs. Furthermore, the transmission of U.S. Pat. No. 6,068,570 does not provide means to produce an infinite number of output speeds.
Thus, it would be advantageous to provide an infinitely variable torque multiplying, substantially constant power mechanical transmission that produces ripple free outputs, requires fewer components to assemble, is easier to manufacture, is adaptable to any prime mover providing ease of shifting, allows power shifting under load, can provide compression braking and can handle substantially more power and torque than prior art transmissions.